1. Field of the Invention
The present invention relates to a digital camera, and more specifically to a digital camera for displaying an image of a photographed object on a monitor.
The present invention relates to a digital camera, and more specifically to a digital camera for determining optimal exposure amount on the basis of an image signal of the photographed object.
2. Description of the Prior Art
In a digital camera, when a shutter button is pressed, a YUV signal is generated on the basis of an RGB signal obtained by pre-exposure of an image sensor, and an optimal exposure amount is determined such that an integration value of the Y signal (a luminance evaluation value) satisfies a predetermined condition. Main exposure of the image sensor is performed according to the optimal exposure amount, and the YUV signal based on the RGB signal obtained by the main exposure is recorded on a recording medium. When a reproducing mode is set, the YUV signal is reproduced from the recording medium, and an image based on the YUV signal is displayed on the monitor.
However, even if an object is photographed with the optimal exposure amount, if color reproducing range of a monitor is narrower than dynamic range of a U signal or a V signal, color saturation may occur on a display image. This problem becomes prominent when there is deviation in a color of the object. Paying attention to a ratio of the RGB signal indicating a red flower photographed in a macro-mode, for example, an R level becomes extremely high, and a G level and a B level become equal to 0. Since the Y signal used for luminance evaluation is generated on the basis of the RGB signal, when the ratio of the RGB signal is extremely distorted, even if the optimal exposure amount is determined such that the luminance evaluation value satisfies the predetermined condition, the level of the R signal obtained by the main exposure becomes still high. Thereupon, the U signal and the V signal based on the main exposure are also out of the color reproducing range of the monitor, and therefore, the color saturation occurs on the display image.
Furthermore, in a prior art in which the optimal exposure amount is calculated such that the luminance evaluation value satisfies the predetermined condition, brightness of a main object image may be short depending on a background. That is, the background of high-luminance (e.g., blue sky in summer) makes the luminance evaluation value high, and the low optimal exposure amount makes the main object image located at the center of the screen dark.